Process of making magnetic amplifiers



Nov. 14, 1961 P. H. CRAIG 3,008,882

PROCESS OF MAKING MAGNETIC AMPLIFIERS Original Filed Feb. 13, 1956INVENTOR. PALMER H .7 CRAIG ATTORNEY United States PatentO 3,008,882PROCESS OF MAKING MAGNETIC AlVIPLIFIERS Palmer H. Craig, 1042 CataloniaAve.,

Coral Gables, Fla. 7 Original application Feb. 13, 1956, Ser. No.565,192, now Patent No. 2,937,351, dated May 17, 1960. Divided and thisapplication Oct. 26, 1959, Ser. No. 852,921

6 Claims. (Cl. 204-) v This invention relates to a process formanufacturing magnetic amplifiers.

Such magnetic amplifiers comprise, in general, a magnetic core materialhaving two or more windings so placed thereon that direct current in thesaturating (input) winding produces partial or complete saturation ofthe core, changing the effective inductance of the power (output)winding and thereby varying the amount of alternating current passed bythat winding.

Other devices, particularly radio tubes and transistors, are commonlyused as amplifiers of audio and radio frequencies. As compared with suchdevices, magnetic amplifiers are extremely rugged, will last almostindefinitely, require no warm-up time or filament or-cathode current,will respond to extremely high frequencies and will withstand muchhigher temperatures. In addition, they can be made to have magneticmemory not possessed by either vacuum tubes or transistors. For thesereasons, magnetic amplifiers are used in computers, switching devices,servo systems, and in numerous other devices' The present application isa division of my application Serial No. 565,192 filed February 13, 1956,issued as Patent No. 2,937,351 on May 17, 1960.

The present manner of manufacturing magnetic amplifiers is to firstproduce ferrite cores by mixing iron oxide powders with other componentssuch as nickel oxide, then pressing this mixture into a toroidal orother desirable shapes and sintering the shaped material in the presenceof oxygen. After the cores have been pro duced, coils of insulated wireare wound thereon by a rather difiicult winding operation requiringspecial winding machines, the number of turns, windings, etc. beingdetermined by the characteristics desired of the magnetic amplifierbeing produced. As can be readily seen, the magnetic amplifiers producedby this method are ex pensive, too costly to be usedas a substitute forrelatively inexpensive radio tubes and transistors and are used only inthose circuits or devices in which only magnetic amplifiers may be used.Asa result, magnetic amplifiers are used today in guided missiles andcomputers where cost is of secondary importance.

The present invention contemplates the manufacture of magneticamplifiers which are inexpensive in cost and susceptible of massproduction methods whereby large quantities of these amplifiers may beproduced simultaneously. A suitable core or a plurality of cores, asmany, as desired toroidal in shape or otherwise, is first deposited byan electroplating process on a backing plate made of insulatingmaterial. This process requires an electrolyte or electroplating bathhaving the capability of depositing cores of nickel-iron or othersuitable alloy, the composition of said electrolyte forming a part ofthis invention. After the cores have been formed, windings are thenwound or deposited thereon, or a conductive paint applied on the coresin a manner described in detail hereinafter.

Therefore, a principal object of the present invention is to producemagnetic amplifiers by a novel method of electro-depositing the cores inanelectroplating operation whereby from a single to hundreds orthousands of such units may be produced simultaneously.

A further object of the present invention is to provide following hasbeen found effective.

3,008,882 Patented Nov. 14, 1961 ICC magnetic amplifiers described asabove wherein an electrolyte of certain composition is utilized, whichresults in the depositing of cores having the desired iron and nickelcontent.

A further object of the present invention is to provide a method ofmanufacturing magnetic amplifiers which are light in weight, rugged inconstruction and inexpensive in cost.

A still further object of the present inventionis the provision of amethod of manufacturing magnetic amplifiers characterized as above whichmay be used in radio and television circuits, computers, servo systems,switching devices, etc, and can serve as memory devices in mechanismsrequiring such a characteristic.

With these and other objects in view, as will appear hereinafter, myinvention consists of certain combinations and processes as will behereinafter described in detail in connection with the accompanyingdrawing and particularly set forth in the appended claims.

In the drawing:

FIGURE 1 is a plan view of a normal toroidal core mounted on a backingplate.

FIGURE 2 is a sectional view taken along the line 2-2 of FIGURE 1.

FIGURE 3 is a similar view to that of FIGURE 2.

showing a modified form of my magnetic amplifier.

FIGURE 4 is a top plan view of a still further modification of theinvention.

FIGURE 5 is a sectional view taken along the line 55 of FIGURE 4. i

As in the normal electroplating and electro-depositing processes thereare required an electrolytic bath, a cathode, an anode, and a source ofelectrical energy whereby a flow of ions is created carrying a metallicdeposit of desired characteristic from the anode to the cathode. Fordepositing an alloy of approximately 40% iron and'60% nickel at thecathode, an electrolyte comprising of the G./l. Nickelous sulfate,crystals 180-200 Nickelous chloride, crystals 40.- -Ferrous fluorborate2- 40 Boric acid 20- '40 Suitable wetting agent. 2 Q

Examples of suitable wetting agents are sodium lauryl sulphate, orphotographic wetting agents. In general sulfonic acids or their saltsprepared from aromatic petroleum compounds, alkylated withmonochlorinated kerosene, and in turn sulfonated may be used.

The pH of the above solution should .be 2.5 to 3.5 and itshould be usedat a temperature of 50 to 60 degrees centigrade. Ferrous sulphatecrystals can be used instead of the ferrous fluoroborate, using the sameconcentrations. To obtain higher percentages of iron in theironnickelalloy which is being plated, use higher concentrations of the ferroussalt. When using ferrous sulphate, add 15 g./l. of nickel tfluoroborateto assist in keeping any ferric iron formed in solution as a complex.The wetting agent is used to prevent pitting of the deposit. Higherrates of deposition can be obtained by omitting the nickel sulfate andusing sufiicient nickel chloride to make the same total nickel content.The bath should be treated with activated carbon in a quantity ofapproximately 4 g./l. of solution, and the solution filtered to removethe carbon. This is to remove harmful organic materials, which may bepresent in case the formula is compounded from technical gradematerials. The higher the iron percentage the harder it is'tokeep thebath in balance.

Anodes should be an alloy of iron-nickel in the same ratio as thatdesired in the plated material. The anode have been thoroughly washed toremove organic materials.

My invention allows the use of diiferent techniques for producingditferentrand special types of amplifiers.

Referring to FIGURE 1, which depicts a typical toroidal vcore 11, Ibegin with an'insulated plastic backing plate which is then coated witha conductive material, such as copper, silver, graphite or,othenconductive materials.

Thebooklet PrintedCircuit Techniques which is National Bureau of,Standards Circular 468, published by the U.'S."' Department ofCommerce, gives onpages 23 and 24. several suitable. techniques for thechemical depo sition of conductivecoatings, on insulating plates, and onpages. 24-26 suitable methods for depositing such conductive coatingsbyvacuum processes, cathodic sputtering and.,evaporation are. given. .Bythe use of the aforementioned electroly-tic bath, a corevll is thendeposited on..this backing plate either through a template which1imits.;thedeposit to the shape and sizewanted or by over thetop of thedeposited cores (assuming a large number of cores were depositedsimultaneously), such backing'plate having been:covered with somesuitable cement or adhesive, normally one of the commonly used plastic.cements. Thedepositcd cores will adhere thereto after the cement dries.Then the new backing plate carrying :the deposited cores is separatedfrom the original backing plate and the graphite is dusted or removedtherefrom by selective chemical baths which will remove such con.ductive materials Without-removing the deposited core material. Thereis now left an insulator plate on which there ,are affixed the depositedcores in whatever shape and sizedesired. 'This shape and size have, ofcourse,

,beencontro-lled by the original template or masking technique. Anyparafiin remaining on the cores 11 is removed by immersion in benzine orother-suitable solvent. After the deposition of the core 11, aninsulating film 13 is placed thereon as'by spraying an acrylic resin(plastic) over the desiredarea.

The next step in the present, process, is the depositing ofmwindings on,core 11. By using a masking technique a suitable conductive paint ispainted or sprayed on the cores in the form of individual wires. Inthisoperation a series of parallel conductivepaths or wires 12 arepositionedon the cores slightly departing from a perpenidicular to, the-,axis, ofithecore onwhichthey are being placed. ,There will be as manyof. these parallel wires as .there are to. be turnsron this winding.These wires extend over the edge of the core and then terminate eitherina rivet, 14 (see FIGURE 2) extending through the insulating' backingplate 10 or in a hole 15 (see'FIGURE 3) j formedat that point, therebeing a hole 15 or rivet 14, for each terminal of each turn of such wire12. Thus if there were to be 100 turns in that winding, there wouldbeZOO such holes 'or rivets, .all being formed with one operation. Inthe case of the rivets 14, as shown by FIGURE 2, the. turns make contactelectrically with the rivets 14. In the. case of the holes, as, shown byFIGURE 3, these holes. 15 can be treated with conductive paint, so that.there is a conductive path 16, from front surface to there-ar surface ofthe insulatingbacking plate, such pathv being .confined, of course, tothat particular spot, there being in the case of 100 turns, 200 suchconductive paths. Now thebacking plate is turned over and another seriesof; such turns orwire 17 deposited on the opposite side, each makingcontact electrically with the cbnductive holes 15 or rivets 14 in theplate 10, so that these wires form the other. side of the turns. Thetemplate or maskingte'chniques should, of. course, include a connectingcore-before starting to apply the windings.

deadfrom each end-of such a coil, or the'coilcouldbe tapped at anydesired place, by a connecting lead being placed there. Electroplatingtechniques could, of course, be substituted for the conductive paint. Inthe instance where the plated alloy is of high electrical resistance itmay not be necessary to :insulate the core before applying the windings,"but it has been found: necessary in most instances to insulatethecore'.before the windings are applied. This caneasilyibe done byapplying an insulating varnish, lacquer, plastic or other suitable coaton the Many other techniques .of assembly offthe, magnetic coresdeposited bythis electroplatingprocess may obviously be carried out,without departing from the scope of the present in- .vention.

Windings may be applied in the conventional manner as, illustrated byFIGURES 4 and 5 wherein bobbins or .winding devices are .used forwindingcoils of insulated wires 20about the. closed cores 11. In thisinstance, the backing. plate10. is slotted or provided with openingsli,19 -and.21, adjacent the outer and inner sides, respectively .of thecore.-11. The openings 19, 21 are sufiiciently large to permit thebobbin to fit therethrough as the windings Zilare positioned on the:core 11.

Many.windings can be deposited or paintedon simultaneously. Successivelayers of core, insulated from one another, may becasily produced andeach such core layer may be extremely. thin, thus lowering losses andmaking the use of very high frequencies feasible. Successive layers ofwindings each insulated from the other may also be employed. The presentmethod'allows the magnetic amplifier thus made to be a memory device ifsodesired, and a wide variety of formulas in the core i available by theuse of suitable baths in the electroplating operation and the use ofanodes composed of desired alloys.

Y amplifiers.

Having described by invention, what I claim as-new is: l. A method ofmanufacturing nmagnetic amplifiers comprising the placing a core-shapedcoating of conductive material: on an insulated "backing plate,immersing said backing plate in an electrolytic bath to constitute acathode, immersing an anode of magnetic metal alloys in saidelectrolyte, said anode having substantially the same ratio of metals asdesired in the core to be deposited on said backing plate, eifecting the.deposit of said anode material on said conductive coating material .toform a core thereon by applying windings on said core, forming aplurality of electrically conductive paths through said backing plateadjacent said inner and outer edges of said core, forming a plurality of'further electrically conductive paths over said core and the portion ofsaid backing plate over which the core has been deposited, so that theend portions of said further electrically conductive paths join saidfirst named paths to form a continuous electrically conductive coilabout said core.

'2. A method of manufacturing magnetic amplifiers comprising the coatingof an insulated backing plate with an-electrically conductive material,said coatingforming a plurality of core shapes, inserting a plurality ofrivets through said backing plate adjacent said core shapes, immersingsaid backing plate in an electrolyte, immersing an anode of magneticmaterial in said electrolyte; effecting a deposit of particles of saidanode on said coating on said backing plate to form a plurality of coresthereon, applying an insulation material on a portion ofsaid'cores,forming a plurality of conductive paths on said backing plate and onsaid insulation on said cores, said conductive paths being connected tosaid rivets toform continuous coils about each of said cores.

3. A method of manufacturing magnetic amplifiers as defined in claim 1,using an electrolytic composition for depositing said core for themagnetic amplifier comprising 190 parts of nickelous sulfate crystals,60 parts of nickelous chloride crystals, 30 parts of ferrousfluorborate, 30 parts of boric acid and .7 part of a wetting agent.

4. The process of making magnetic amplifiers,.comprising depositingelectrolytically a core material on an insulated backing plate having aconductive coating constituting the cathode while masking said plate todefine the desired shape of the cores, depositing coil half turnportions over the outside of said core and on the opposite side of saidinsulated material, making a series of apertures alongside said cores,and depositing conductive material in said apertures to join thesuccessive half turns of said coil portions on opposite sides of saidplate.

5. The process of making magnetic amplifiers, comprising depositingelectrolytically a nickel-iron alloy core material on an insulatedbacking plate having a conductive coating constituting the cathode,using a mask on said plate to define the desired shape of the cores,transferring the cores to a plate of insulated material, depositing coilhalf turn portions over the outside of said core and on the oppositeside of said insulated material, making a series of apertures alongsidesaid cores, and depositing conductive material in said apertures to joinG./l. Nickelous sulfate, crystals; 180-200 Nickelous chloride, crystals-80 Ferrous fluorborate 2-40 Boric acid 20-40 and a suitable wettingagent, and maintaining a pH of said solution substantially 2.5 to 3.5,and a temperature of substantially to C.

References Cited in the file of this patent UNITED STATES PATENTS1,563,731 Ducas Dec. 1,1925 2,721,822 Pritikin Oct. 25, 1955 2,792,340James May 14, 1957 2,927,066 Schaer Mar. 1, 1960 OTHER REFERENCESPrinted Circuit Techniques, Nat. Bureau of Standards Circular 468,November 15, 1947, pages 17 and 18.

1. A METHOD OF MANUFACTURING MAGNETIC AMPLIFIERS COMPRISING THE PLACINGA CORE-SHAPED COATING OF CONDUCTIVE MATERIAL ON AN INSULATED BACKINGPLATE, IMMERSING SAID BACKING PLATE IN AN ELECTROLYTIC BATH TOCONSTITUTE A CATHODE, IMMERISING AN ANODE OF MAGNETIC METAL ALLOYS INSAID ELECTROLYTE, SAID ANODE HAVING SUBSTANTIALLY THE SAME RATIO OFMETALS AS DESIRED IN THE CORE TO BE DEPOSITED ON SAID BACKING PLATE,EFFECTING THE DEPOSIT OF SAID ANODE MATERIAL ON SAID CONDUCTIVE COATINGMATERIAL TO FORM A CORE THEREON BY APPLYING WINDINGS ON SAID CORE,FORMING A PLURALITY OF ELECTRICALLY CONDUCTIVE PATHS THROUGH SAIDBACKING PLATE ADJACENT SAID INNER AND OUTER EDGES OF SAID CORE, FORMINGA PLURALITY OF FURTHER ELECTRICALLY CONDUCTIVE PATHS OVER SAID CORE ANDTHE PORTION OF SAID BACKING PLATE OVER WHICH THE CORE HAS BEENDEPOSITED, SO THAT THE END PORTIONS OF SAID FURTHER ELECTRICALLYCONDUCTIVE PATHS JOIN SAID FIRST NAMES PATHS TO FORM A CONTINUOUSELECTRICALLY CONDUCTIVE COIL ABOUT SAID CORE.